Mechanical interlock for switches



Oct. 13, 1970 w. c. KARCH MECHANICAL INTERLOCK FOR SWITCHES 3 Sheets-Sheet 1 Filed July 15, 1969 INVENTOR. zi/awrc- 1 ATTORNEY.

Oct. 13, 1970 w. c. KARCH MECHANICAL INTERLOCK FOR SWITCHES 5 Sheets-Sheet 2 Filed July 15, 1969 INVENT R. mm. c. ai,

I iATTQRNEY.

Oct. 13, 1970 w. c. KARCH 3,534,187

IECHANICAL INTERLOCK FOR SWITCHES Filed July 15, 1969 3 Sheets-Sheet 8 H7 7 2 Q i ATTORNEY United States Patent 3,534,187 MECHANICAL INTERLOCK FOR SWITCHES Walter C. Karch, Grafton, Wis., assignor to Square D Company, Park Ridge, 111., a corporation of Michigan Filed July 15, 1969, Ser. No. 841,895 Int. Cl. H01h 33/50 US. Cl. 200-50 9 Claims ABSTRACT OF THE DISCLOSURE The interlock comprises two levers pivoted for independent rocking about parallel axes and driven by electromagnetic starters, respectively, when the starters are energized. A rigid interlock bar interconnects the levers and engages opposed cam tracks so as to float endwise and edgewise. The tracks converge in the direction in which the bar must be moved by the starters, the convergence being so related to the length of the bar that the ends of the bar cannot travel along the tracks in the converging direction concurrently, and thereby prevent operation of either starter when the contacts of the other are closed.

This invention relates to a mechanical interlock for switches, such as electrical starters and the like.

The interlock is comprised of simple working parts, few in number, and so arranged that it can be connected to a pair of starters and interlock them positively in a manner to assure that neither can be moved from open to closed position while the other is closed and the two cannot be closed by concurrent movement from their open positions.

The parts are so constructed and arranged that by substitution of one slightly modified part, the other parts can be mounted thereon in a slightly different relation to each other, whereby the interlock is adapted for interlocking two duplicate switches or starters which are horizontally aligned or are vertically aligned, respectively.

The invention broadly'is an improvement on, and simplification of, the interlock disclosed in US. Pat. No. 3,303,300, issued Feb. 7, 1967.

Various specific advantages of the present invention will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a front elevation of an interlock embodying the principles of the present invention, and showing it interlocking two electric starters in their open positions and arranged side by side in horizontal alignment, part of each of the starters being shown in section for clearness in illustration;

FIG. 2 is a bottom plan view of the structure illustrated in FIG. 1, part of one of the starters being shown in section;

\FIG. 3 is a left side elevation of the structure illustrated in FIGS. 1 and 2 FIG. 4 is a bottom plan view to FIG. 2 showing the position of the parts of the interlock when one of the interlocked starters is open and the other is closed;

FIG. 5 is a left side view of the structure illustrated in FIG. 4;

FIG. 6 is a front elevation of the interlock showing it interconnecting two identical electric starters in their open positions and aligned vertically with each other, part of the starters being shown fragmentarily for clearness in illustration;

FIG. 7 is a bottom plan view of the interlock illustrated in FIG. 6; and

FIG. 8 is a left side elevation of the structure illustrated in FIGS. 6 and 7.

Referring to FIGS. 1 through 5, the interlock, indi- ICC cated generally at 1, is shown interlocking two identical starters 2 which are arranged in horizontal alignment with each other.

Each starter has a switch operator 3 which is driven rearwardly against the restoring force of a return spring, not shown, for closing the switch, not shown, of the starter when the starter is energized. Each operator 3 has a horizontal dead end slot 4 which at its rear end is closed by an abutment wall '5 adapted to engage an associated connecting element of the interlock and move it rearwardly in FIG. 1 when the operator is driven rearwardly by energization.

The interlock 1 comprises an upright base 6 on which is mounted a forwardly projecting support 7, preferably in the form of an elongated fiat plate extending at a right angle to the plane of the base 6.

Mounted on the support 7 are a pair of rock levers 8 arranged one at each face of the support 7. The rock levers are connected to the support 7 by suitable pivots 9 for rocking about parallel axes. Each rock lever 8 carries at its inner end a connecting element 10, above mentioned, 'which is arranged to be engaged and driven or urged rearwardly by the wall 5 when the operator is moved towerd its switch closing position.

In the opposite ends of the support 7 are two openings 12 which are identical in shape and symmetrically ararranged with respect to the longitudinal midportion of the support 7.

The wall portions of the openings 12 which are outermost endvvise of the support 7 face generally toward each other, respectively, and provide cam tracks 14 which coverge in a direction away from the base 6, or forwardly of the support 7 in FIG. 1.

A rigid elongated interlock bar 15 cooperates with the cam tracks 14 and the rock levers 8 to interlock the levers in certain relative positions. The rock levers 8 are arranged on the opposite sides of the support 7, and

the support is provided at its midportion with an opening 16. The rock bar 15 is bent intermediate its ends so that one end portion lies alongside one face of the support 7, the other end portion lies alongside the other face, and its central portion extends through the opening 316. Ample clearance is provided between the lock bar 15 and the walls of the opening 16 so that they do not interfere with the operation of the bar 15.

At its opposite ends the lock bar 15 is provided with followers 17, respectively, each of which is the form of a roller which is mounted on a pin 17a and which rolls along the cam track 14 of its associated opening 12.

:Each cam track 14, at the end nearest the base 6, has a seating portion 18, which is of arcuate shape to fit approximately the periphery of a follower 17 on the associated end of the rock bar 15, and has a locking portion 19 joining the seating portion in end to end rela tion. The portions 19 of the two cam tracks 14' converge in a direction away from seating portions 18 toward their opposite ends.

The distance between the followers 17, and the shape and contour of the cam tracks 14 are such that when the follower 17 at one end of the bar 15 is in the seating portion 18 of its associated cam track 14, the bar can swing about the axis of that follower as-a center and the follower 17 at the other end of the bar 15 can travel along, and in engagement with, the locking portion 19 of its associated cam track 14. On the other hand, neither follower 17 can travel along the locking portion 19 of its associated track when the opposite follower 17 is engaging the locking portion 19 of its associated cam track.

Thus the two followers 17 cannot concurrently travel along the locking portions of their respective tracks. It is only when one follower 17 is in the seating portion of its track that the other follower can travel along the locking portion of the other track, and thereby permit the rock bar to swing about the axis of the seated follower.

To interconnect the rock levers 8 and the opposite ends of the lock bar 15, respectively, each rock lever is provided with a slideway 20 in the form of a yoke in which is slidable a slide block 21 which is rockably mounted on the pin 17a and is slidable radially of the rocking axis. This connects the end of the bar 15 to its associated rock lever 8 so that that end is movable radially of the rocking axis of the rock lever and concurrently circumferentially of the rocking axis. Since both ends of the rock bar 15 are supported in like manner, the rock bar is floatingly supported by the rock levers and cam tracks for movement endwise of the bar 15 and endwise of the cam tracks 14 and thus edgewise of the bar.

Each follower pin 17a extends through the associated slide block 21 and suitable washers 22 are disposed between the opposite faces of support 7 and the inner faces of the lock bar. For convenience in servicing, the outer end of each follower pin 17a carries a snap washer 23, which engages the outer face of the slide block 21 and secures the parts together axially of the follower.

In operation, if the element of either rock lever 8 is depressed by its operator 3, the end of the lock bar connected to that lever 8 is moved so that its associated follower 17 moves away from the base 6 along the locking portion 19 of its associated cam track 14, the follower 17 at the other end of the bar remaining in, or being pushed into, firm engagement with, the seating portion 18 of its associated cam track. For example, as illustrated in FIG. 5, if the connecting element 10 of the upper lever 8 is depressed toward the base 6 by the operator 3 of the right hand starter 2 while the lower lever 8 remains in its neutral position, the lower end of the lock bar 15 is driven downwardly, disposing the follower 17 at the lower end of the lock bar 15 in firm seating engagement with the seating portion 18 of its cam track. Thereupon the upper follower travels freely along the locking portion 19 of its cam track 14 away from the base 6 by swinging the lock bar about the axis of the lower follower.

If, while the upper follower 17 is in engagement with the locking portion 19 of its cam track 14, the right-hand starter 2 is energized to close its switch, the follower 17 at the lower end of the rock bar 15 is constrained from moving out of its associated seating portion and toward the locking portion 19 of its cam track 14, due to the rigidity of the bar 15 and the convergence of the locking portions 19 in a direction away from the base 6 and seating portions 18. Therefore, the lower rock lever 8, and hence the operator 3 of the starter connected thereto, cannot be moved in the direction to permit closing of the associated starter.

A like situation is presented if the lower rock lever 8 shown in FIG. 5 is first operated by its starter.

If an attempt is made to operate both starters, and therefore both operators 3 and their rock levers 8, concurrently, then obviously the followers 17 at both ends of the bar 15 attempt to move into engagement with the locking portions 19 of the cam tracks, respectively, concurrently. Since the distance between the locking portions 19 is shorter than the distance between the followers, the concurrent operation is prevented.

In order to stabilize the operation of the interlocking mechanism and return the parts to the starting position, the rock levers and lock bar 15 are biased by a spring 24 to a position in which both followers 17 are at the seating portions 18 of their respective cam tracks 14, though, as noted above, neither follower is necessarily fully seated against its particular seating portion in the neutral position of the bar 15. The spring 24, as shown, has its opposite ends connected between the base 6 and the longitudinal center of the lock bar 15, respectively.

In some cases it is desirable to arrange switches in vertical alignment in which case the structure illustrated in FIGS. 6 through 8 is provided. The structure is essentially the same as that illustrated in FIGS. 1 through 5, and is shown as cooperating with two starters 2a arranged one above the other in vertical alignment and at the same side of the interlock. Those parts of the modified form of the interlock which are the same as in the form illustrated in FIGS. 1 through 5 are not specifically described but are indicated by the same reference numerals with the suflix a added.

Each starter has an operator 3a which is engaged by an associated operating element 1011 on its rock lever 8a of the interlock.

The interlock comprises a base 26 and support 27, longer than the base 6 and support 7, the support 27 having the pivots 9a of its rock levers 8a arranged outwardly toward the opposite ends of the plate 27 from the cam openings 12a, as distinguished from inwardly from the openings 12 in FIGS. 1 through 5. The rock levers 8a are reversed in position endwise of the support so that their operating elements 10a are disposed outwardly from their pivots beyond the ends of the plate 27, and their guide portions 20:: disposed inwardly from their pivots 9a. Likewise they are turned so that the connecting elements 10a face in the same direction from the plane of the support 27 so that they can engage operators 3a at the same side of the support 27. The structure functions in the same manner as the form illustrated in FIGS. 1 through 5.

Having thus described my invention, I claim:

1. A mechanical interlock comprising:

a support;

a pair of opposing cam tracks spaced apart from each other and facing in opposite directions, each track having a seating portion near one of its ends and a contiguous locking portion extending therefrom toward the other of its ends, the locking portions of said tracks converging from their seating portions toward said other ends;

an elongated rigid interlock bar;

cam followers mounted thereon in fixed spaced relation to each other endwise of the bar and engageable with the tracks, respectively;

rock levers mounted on the support for rocking independently of each other about axes, respectively, which are fixed in position relative to the support and are spaced from each other in a direction generally endwise of the bar, each lever from an inoperative position to an operative position;

connecting means drivingly connecting each follower to its associated rock lever for movement circumferentially therewith and radically relative thereto, concurrently, about'its associated rocking axis, and thereby, in conjunction with the cam tracks, supporting the bar for limited floating movement endwise of the bar and endwise of the tracks;

biasing means biasing the rock levers to their inoperative positions and the bar to an inoperative position;

the contour and convergence of the tracks and the distance between the followers being related so that when either follower is seated in the seating portion of its associated track the other follower can travel along the locking portion of its associated track toward said other end thereof, but neither follower can travel along the locking portion of its associated track toward its said other end when the other follower is engaged with the locking potrion of its associated track.

2. The structure according to claim 1 wherein the bar is supported for limited floating movement endwise of the bar relative to the levers and endwise of the tracks, so that the bar is moved endwise when either follower is moved by its rock lever toward said other end onto the locking portion of its associated track while the other rock lever remains in its inoperative position, and thereby disposes the other follower on the seating portion of its associated track.

3. The structure according to claim 1 wherein a biasing spring is connected at one end to the midportion of the bar and at the other end to the support and urges the bar to a position wherein its followers are at the seating portions of the tracks, respectively.

4. The structure according to claim 1 wherein the support includes an elongated relatively flat plate, the plate has a central opening therethrough between the rocking axes of the levers, and the bar is shaped so that it has end portions which lie alongside opposite faces of the plate, respectively, and a midportion which extends through said opening and is out of contact with the walls thereof in all positions of the bar.

5. The structure according to claim 4 wherein the levers have operating elements, respectively, extending outwardly away from the plane of the plate for connection to operators of devices to be interlocked, respectively.

6. The structure according to claim 5 wherein said operating elements extend outwardly in opposite directions, away from opposite faces of the plate.

7. The structure according to claim '5 wherein said operating elements extend outwardly in the same direction from the same face of the plate for connection to operators of devices when the operators are disposed at the same side of the plane of the plate.

8. The structure according to claim 1 wherein the support is a relatively fiat plate and has passages of the same shape therethrough near its ends, respectively, and symmetrically arranged relative to each other and to the midportion of the plate; and

respective corresponding wall portions of the passages,

respectively comprise the cam tracks.

9. The structure according to claim 1 wherein the connecting means for each follower comprises a slideway in the associated rock lever extending radially thereof, and a slide member is slidable in said slideway and drivingly connected to the bar.

References Cited UNITED STATES PATENTS 3,303,300 2/1967 Turnbull 200-503 ROBERT K. SCHAEFER, Primary Examiner M. GINSBURG, Assistant Examiner 

